Enthalpies will be obtained for the transfer of various proteins from dilute buffer to aqueous alcohol solutions at low concentrations of the cosolute. Enthalpies of transfer of N-acetylated amino acids, their amides and several other model substances from buffer to the same alcohol solutions will also be determined. These model substances will provide a set of enthalpies of transfer from buffer to alcohol solution for each amino acid residue comprising common proteins. Using these model compound values together with the accessibilities of various groups of a protein determined by computer analysis of known crystal structures of proteins it is possible to calculate transfer quantities for whole proteins. Comparison of these values to those experimentally determined provides a test of the quality of the available models of the accessibility of the protein surface to solvent. Values for accessibility of denatured conformations will also be determined.